Damage to the barrel bridge - leave or repair?

[SpringMangler]

I've had an old 1914 trench watch sitting in a box for a few months. It runs intermittently and is filthy so today I thought I'd strip it down for cleaning. I've just picked up a nice condition National MK VR so this watch will be the guinea pig.

The movement is an unidentified Fontainemelon, which is referred to as Fontainmelon 2 on David Boettcher's website Watch Movement Identification .

A few small battles stripping it down; the cannon pinion stuck as though epoxied on was the worst part. Whilst giving the parts a pre-clean I noticed something strange on the barrel bridge. It looks as though something in the keyless works, most probably the clutch, has worn through the bridge under the crown wheel. I can't see any noticeable marks on the crown wheel but this wear must have been happening for years. The watch winds and the hands set though I did notice that the stem moves quite a bit as there is no stem tube in the case. 

As this is an old movement it's going to be nigh impossible to find parts. So, should I just leave as is or is a repair at all possible? The latter would be way outside of my ability so I would need to find someone to repair it. If the answer is 'don't bother' I may just take that sharpness off. Secondly, should there be a case tube on this old silver case?

Oh, and the four deep scratches that you can see are replicated on the main plate and the inside of the barrel!

Edited October 5, 2022 by SpringMangler

[nickelsilver]

The worn through area won't hurt anything, and a repair would be extremely difficult and almost certainly resort to soldering metal and remachining, which is kind of hokey (soldering) and a lot of work (machining).

 

What has happened is the stem has worn the bearing area* at the edge of the bridge and quite certainly on the mainplate as well. That's the play you've noticed. The solution is to make a new stem with a larger diameter there so that it has minimal play. Not a big job for someone accustomed to it.

 

*When installing a crown most folks will hold the stem in a pinvice on this portion (the bearing nearest the thread). If the pinvise has hard steel jaws and they are of the pointy type, it will likely dig in and raise up 4 little teeth which will certainly eat away at these areas over the coming years of winding. It's important to make sure the pinvice does not damage the stem (I always hold the stem in the lathe or in a pinvice that takes lathe collets).

 

But a regular old stem with no damage can eventually wear these parts too. The solution is still the same.

 

 

[SpringMangler]

Many thanks for the very detailed reply, it is really appreciated. I don't have a lathe at the moment but will try and find someone to machine one for me.

[anilv]

When reassembling, try and see if you can support the stem at the edge of the movement, where the stem enters the movement. This will help to stabilise the stem and avoid further damage. A bit of copper/brass is easy to work into a tube and you can probably epoxy it in place. Hell, even a piece of plastic sheathing like the bit around an electrical wire will be better than nothing as I don't think this watch will be worn on a daily basis. The idea is to avoid further damage.

Also the case may need a crown tube as that also helps stabilise the stem/case/movement interface.

Anilv

Edited October 6, 2022 by anilv